Semiconductor-on-diamond devices and methods of forming

ABSTRACT

The present invention provides semiconductor-on-diamond devices, and methods for the formation thereof. In one aspect, a mold is provided which has an interface surface configured to inversely match a configuration intended for the device surface of a diamond layer. An adynamic diamond layer is then deposited upon the diamond interface surface of the mold, and a substrate is joined to the growth surface of the adynamic diamond layer. At least a portion of the mold can then be removed to expose the device surface of the diamond which has received a shape which inversely corresponds to the configuration of the mold&#39;s diamond interface surface. The mold can be formed of a suitable semiconductor material which is thinned to produce a final device. Optionally, a semiconductor material can be coupled to the diamond layer subsequent to removal of the mold.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/983,801, filed on Jan. 3, 2011, which is a continuation of U.S.patent application Ser. No. 11/876,326, filed on Oct. 22, 2007, which isa continuation of U.S. patent application Ser. No. 11/323,187, filedDec. 29, 2005, now published as United States Publication No.2006/0186556, which is a divisional of U.S. patent application Ser. No.10/846,847, filed May 13, 2004, now issued as U.S. Pat. No. 7,132,309,which is a continuation-in-part of U.S. patent application Ser. No.10/421,369, filed on Apr. 22, 2003, now issued as U.S. Pat. No.7,011,134, which is a continuation-in-part of U.S. patent applicationSer. No. 10/002,395, filed on Oct. 19, 2001, now issued as U.S. Pat. No.6,814,130, which is a continuation-in-part of U.S. patent applicationSer. No. 09/687,444, filed on Oct. 13, 2000, now issued as U.S. Pat. No.6,659,161, each of which are incorporated herein by reference in theirentireties.

FIELD OF THE INVENTION

The present invention relates to semiconductor devices incorporatingsuper-hard materials, such as diamond or diamond-like substances, andmethods for making such devices. More particularly, the presentinvention relates to the use of vapor deposition for makingsemiconductor devices incorporating diamond materials.

BACKGROUND OF THE INVENTION

Diamond and diamond-like substances have many properties, such as wearresistance, thermal conductivity, electrical resistivity, acoustictransmission, and corrosion inertness, which make them desirable for avariety of industrial applications. To this end, diamond anddiamond-like substances have been incorporated into tools for variouspurposes such as saw blades, drill bits, and electronic components suchas surface acoustic wave filters. Methods for incorporating diamond ordiamond-like materials into a tool can include known processes such aschemical vapor deposition (CVD) and physical vapor deposition (PVD).

Various CVD techniques have been used in connection with depositingdiamond or diamond-like materials onto a substrate. Typical CVDtechniques use gas reactants to deposit the diamond or diamond-likematerial in a layer, or film. These gases generally include a smallamount (i.e. less than about 5%) of a carbonaceous material, such asmethane, diluted in hydrogen. A variety of specific CVD processes,including equipment and conditions, are well known to those skilled inthe art.

In forming a layer of diamond, or diamond-like material on a substrateusing CVD techniques, a plurality of diamond grains, or “seeds,” may befirst placed upon the substrate surface. The placement of such seeds maybe accomplished using CVD itself such as by applying a voltage bias, bypolishing with micron-sized diamond, or by other methods known in theart. These seeds act as diamond nuclei and facilitate the growth of adiamond layer outwardly from the substrate as carbon vapor is depositedthereon. As a result, the growing side of the diamond layer becomesincreasingly coarse in grain size, and must ultimately be ground andpolished to a smooth finish such as by a mechanical means, in order tobe suitable for many industrial applications. However, as diamond anddiamond-like substances are among the hardest known materials, suchmechanical grinding and polishing is difficult and tedious. Moreover,the cost of polishing often exceeds the cost for making the diamond filmitself. In addition, mechanical polishing inevitably introducesmicro-cracks or variations on the diamond surface. Such cracks andvariations are detrimental to certain applications.

The semiconductor industry has recently expanded efforts in producingsemiconductor-on-insulator (SOI) devices. These devices allow forelectrical insulation between an underlying substrate and any number ofuseful semiconductor devices. Typically, these SOI devices can includeinsulating layers with poor thermal conductivity, high degree of thermalexpansion mismatch, and/or difficulties in epitaxial growth of siliconor other semiconductor materials. In light of some of thesedifficulties, various efforts have explored using diamond as theinsulating layer with some success. However, such devices continue tobenefit from further improvement such as decreasing manufacturing costs,improving performance, and the like.

As such, SOI devices and methods for making diamond containing SOIdevices which have improved performance and reduced production costscontinues to be sought.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides semiconductor-on-diamond(SOD) devices and methods for making such devices that address many ofthe difficulties mentioned above. As such, the present devices andmethods are capable of providing SOD devices with improved insulatingproperties and which are particularly suitable for use in insulatingsemiconductor devices and the like.

In one aspect of the present invention, a SOD device can include asubstrate having an adynamic diamond layer on the substrate. A devicesurface of the adynamic layer can be oriented distal to the substrate.Further, a semiconductor layer can be coupled to the device surface ofthe diamond layer. The semiconductor layer can be formed directly on theintermediate layer or formed on an intermediate layer.

In an additional aspect, the semiconductor layer can be coupled using anintermediate layer such as aluminum nitride, chromium nitride, silicon,silicon carbide, silicon nitride, tungsten carbide, gallium nitride,diamond-like carbon, and composites thereof.

In one detailed aspect, the device surface can have a surface roughness(Ra) from about 1 nm to about 1 μm.

As a general matter, the method of making an SOD device in accordancewith the present invention begins by providing a mold having aninterface surface configured to inversely match a configuration intendedfor a device surface of the diamond SOD device. An adynamic diamondlayer can then be grown on the diamond interface surface of the moldusing a vapor deposition technique. As diamond growth proceeds, theadynamic diamond layer receives a growth surface opposite the devicesurface, which is then joined to a substrate or support layer. Asemiconductor layer can also be coupled to the device surface.

In one embodiment, at least a portion of the mold can be removed. Insome cases, the mold can be thinned to form either the semiconductorlayer and/or the intermediate layer. Thus, the mold can be chosen of amaterial suitable for incorporation into the final SOD device.Alternatively, the mold can be completely removed and a semiconductorlayer, and optional intermediate layer, formed on the exposed diamonddevice surface.

In still another alternative aspect, a method of making a SOD device caninclude providing a mold having an interface surface. An adynamicdiamond layer can be grown on the interface surface using a vapordeposition technique, said adynamic diamond layer having a growthsurface opposite the interface surface. A semiconductor layer can alsobe coupled to the growth surface of the adynamic diamond layer.

There has thus been outlined, rather broadly, the more importantfeatures of the invention so that the detailed description thereof thatfollows may be better understood, and so that the present contributionto the art may be better appreciated. Other features of the presentinvention will become clearer from the following detailed description ofthe invention, taken with the accompanying drawings and claims, or maybe learned by the practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side cross-sectional view of an SOD device in accordancewith an embodiment of the present invention.

FIG. 2 is a side cross-sectional view of an SOD device in accordancewith an alternative embodiment of the present invention.

FIGS. 3A through 3D show side cross-sectional views illustrating onemethod of producing SOD devices in accordance with the presentinvention.

FIGS. 4A through 4C show side cross-sectional views illustrating analternative method of producing SOD devices in accordance with thepresent invention.

The above figures are provided for illustrative purposes only. It shouldbe noted that actual dimensions of layers and features may differ fromthose shown.

DETAILED DESCRIPTION

Before the present invention is disclosed and described, it is to beunderstood that this invention is not limited to the particularstructures, process steps, or materials disclosed herein, but isextended to equivalents thereof as would be recognized by thoseordinarily skilled in the relevant arts. It should also be understoodthat terminology employed herein is used for the purpose of describingparticular embodiments only and is not intended to be limiting.

It must be noted that, as used in this specification and the appendedclaims, the singular forms “a,” and, “the” include plural referentsunless the context clearly dictates otherwise. Thus, for example,reference to “an intermediate layer” includes one or more of suchlayers, reference to “a carbon source” includes reference to one or moreof such carbon sources, and reference to “a CVD technique” includesreference to one or more of such CVD techniques.

DEFINITIONS

In describing and claiming the present invention, the followingterminology will be used in accordance with the definitions set forthbelow.

As used herein, “super hard” and “superabrasive” may be usedinterchangeably, and refer to any crystalline, or polycrystallinematerial, or mixture of such materials which has a Moh's hardness ofabout 8 or greater. In some aspects, the Moh's hardness may be about 9.5or greater. Such materials include but are not limited to diamond,polycrystalline diamond (PCD), cubic boron nitride, polycrystallinecubic boron nitride (PCBN) as well as other super hard materials knownto those skilled in the art. Super hard materials may be incorporatedinto the present invention in a variety of forms including particles,grits, films, layers, etc.

As used herein, “substrate” refers to a non-diamond surface, to whichvarious materials can be joined in forming an SOD device. The substratemay be any shape, thickness, or material, required in order to achieve aspecific result, and includes but is not limited to metals, alloys,ceramics, and mixtures thereof. Further, in some aspects, the substrate,may be an existing semiconductor device or wafer, or may be a materialwhich is capable of being joined to a suitable device. In someadditional aspects, the substrate can be a material that once bonded toan adynamic diamond layer, has sufficient integrity to prevent the layerfrom changing shape once separated from the mold upon which it was made.

As used herein, “metallic” refers to any type of material or compoundwherein the majority portion of the material is a metal. As such,various oxide, nitride, and carbide compounds, as well as any othermaterial or compound, containing a greater non-metal portion than metalportion are not considered to be “non-metallic.” Examples of variousmetals considered to be particularly useful in the practice of thepresent invention include, without limitation: aluminum, tungsten,molybdenum, tantalum, zirconium, vanadium, chromium, copper, and alloysthereof.

As used herein, “ceramic” refers to a non-diamond, non-metallic,material, which is hard, heat resistant, corrosion resistant, and can bepolished to have a surface roughness (Ra) of less than about 1micrometer. Further, as used herein, “ceramic” materials may contain atleast one element selected from the group consisting of: Al, Si, Li, Zn,and Ga. Oxides, nitrides, and various other compounds which include theabove recited elements are well known as ceramics to those skilled inthe art. Additional materials considered to be “ceramics” as usedherein, such as glass, are known to those skilled in the art. Examplesof specific ceramics useful in the present invention include withoutlimitation, Si, SiO₂, Si₃N₄, Al₂O₃, AlN, BN, TiN, ZrN, GaAs, GaP,LiTaO₃, LiNbO₃, ZnO, glass, such as soda glass, etc.

As used herein, “interface surface” refers to the surface of a mold, orephemeral mold, or other layer of material conveying the shape of themold, upon which materials used in the fabrication of a diamond layer orfilm are deposited. Such materials include diamond or othersuperabrasive particles, as well as peripheral materials used tofacilitate diamond layer growth using a CVD technique, such as diamondnucleation enhancers. The interface surface can be the immediate surfaceof the mold or may include an exposed surface resulting from a thinlayer of material formed thereon which does not significantly affect thesurface contours and roughness of the original mold surface, and thusconveys the configuration thereof. Such thin layers can includenucleation enhancing materials, piezoelectric materials, and any othermaterial which can be formed in sufficiently thin layers so as to retaina substantially identical surface as the original smooth mold surface.

As used herein with respect to a mold, “outside surface” refers to asurface of the mold which is not in direct contact with the diamondlayer.

As used herein, “adynamic” refers to a type of layer which is unable toindependently retain its shape and/or strength. For example, in theabsence of a mold or support layer, an adynamic diamond layer will tendto curl or otherwise deform when the mold or support surface is removed.While a number of reasons may contribute to the adynamic properties of alayer, in one aspect, the reason can be the extreme thinness of thelayer.

As used herein, “nucleation enhancer” refers to a material, whichincreases the quality of a diamond layer formed from a plurality ofdiamond nuclei using a CVD process. In one aspect, the nucleationenhancer may increase the quality of the diamond layer by reducingmovement or, or immobilizing diamond nuclei. Examples of nucleationenhancers include without limitation, metals, and various metalliccompounds, as well as carbides and carbide forming materials.

As used herein with respect to a nucleation enhancer layer and anintermediate layer, “thin” refers to the thickness or depth of the layerbeing sufficiently small so as to not substantially interfere with thetransfer of the intended configuration from the interface surfaceconfiguration to the device surface. In one aspect, the thickness of thenucleation enhancer may be less than about 0.1 micrometers. In anotheraspect, the thickness may be less than 10 nanometers. In another aspect,the thickness may be less than about 5 nanometers.

As used herein, “device surface” refers to the surface of a diamondlayer which contacts a semiconductor or other electronic device.

As used herein, “diamond layer” refers to any structure, regardless ofshape, which contains diamond-containing materials which can beincorporated into a SOD device. Thus, for example, a diamond filmpartially or entirely covering a surface is included within the meaningof these terms. Additionally, a layer of a material, such as metals,acrylics, or composites, having diamond particles disbursed therein isincluded in these terms.

As used herein, “diamond-containing materials” refer to any of a numberof materials which include carbon atoms bonded with at least a portionof the carbons bonded in at least some sp³ bonding. Diamond-containingmaterials can include, but are not limited to, natural or syntheticdiamond, polycrystalline diamond, diamond-like carbon, amorphousdiamond, and the like. Most often, the diamond layers of the presentinvention are formed as diamond-like carbon and/or amorphous diamond.

As used herein, “vapor deposited” refers to materials which are formedusing vapor deposition techniques.

As used herein, “vapor deposition” refers to a process of depositingmaterials on a substrate through the vapor phase. Vapor depositionprocesses can include any process such as, but not limited to, chemicalvapor deposition (CVD) and physical vapor deposition (PVD). A widevariety of variations of each vapor deposition method can be performedby those skilled in the art. Examples of vapor deposition methodsinclude hot filament CVD, rf-CVD, laser CVD (LCVD), metal-organic CVD(MOCVD), sputtering, thermal evaporation PVD, ionized metal PVD (IMPVD),electron beam PVD (EBPVD), reactive PVD, and the like.

As used herein, “chemical vapor deposition,” or “CVD” refers to anymethod of chemically depositing diamond or other particles in a vaporform upon a surface. Various CVD techniques are well known in the art.

As used herein, “CVD passive material” refers to a material which doesnot allow substantial deposition of diamond or other materials using CVDmethods directly to the material. One example of a CVD passive materialwith respect to deposition of diamond is copper. As such, during CVDprocesses carbon will not deposit on the copper but only on CVD activematerials such as silicon, diamond, or other known materials. Thus, CVDpassive materials can be “passive” with respect to some materials andnot others. For example, a number of carbide formers can be successfullydeposited onto copper.

As used herein, “inversely correspond” refers to the inverserelationship between the configuration of a diamond device surface, andthe configuration of a mold's interface surface from which the devicesurface was made, when such surfaces are oriented in the same direction.In other words, when a device surface is formed at the interface surfaceof a mold, the configuration of each will inversely correspond to theother when the surfaces are separated and faced in the same direction.In some instances, the inverse correspondence may result in a mirrorimage.

As used herein, “nucleation side,” “nucleation surface,” and similarterms may be used interchangeably, and refer to the side or surface of adiamond layer at which nucleation of diamond particles originated.Otherwise described, the nucleation surface of a diamond layer is theside or surface, which was first deposited upon the interface surface ofa mold. In many instances, the nucleation surface may become the devicesurface of the tool.

As used herein, “growth side,” “grown side,” and “grown surface” may beused interchangeably and refer to the surface of a superabrasive film orlayer which is grows during a CVD process.

As used herein, “Ra” refers to a measure of the roughness of a surfaceas determined by the difference in height between a peak and aneighboring valley. Further, “Rmax” is a measure of surface roughness asdetermined by the difference in height between the highest peak on thesurface and the lowest valley on the surface.

As used herein with respect to an identified property or circumstance,“substantially” refers to a degree of deviation that is sufficientlysmall so as to not measurably detract from the identified property orcircumstance. The exact degree of deviation allowable may in some casesdepend on the specific context. Thus, for example, a source materialwhich has a composition “substantially” that of a particular region maydeviate in composition or relevant property by experimental error up toseveral percent, e.g., 1% to 3%.

Concentrations, amounts, and other numerical data may be expressed orpresented herein in a range format. It is to be understood that such arange format is used merely for convenience and brevity and thus shouldbe interpreted flexibly to include not only the numerical valuesexplicitly recited as the limits of the range, but also to include allthe individual numerical values or sub-ranges encompassed within thatrange as if each numerical value and sub-range is explicitly recited.

As an illustration, a numerical range of “about 1 micrometer to about 5micrometers” should be interpreted to include not only the explicitlyrecited values of about 1 micrometer to about 5 micrometers, but alsoinclude individual values and sub-ranges within the indicated range.Thus, included in this numerical range are individual values such as 2,3, and 4 and sub-ranges such as from 1-3, from 2-4, and from 3-5, etc.

This same principle applies to ranges reciting only one numerical value.For example, a range recited as “less than about 5 micrometers” shouldbe interpreted to include all values and sub-ranges between 5micrometers and 0 micrometers, including the value of 0 micrometers.Furthermore, such an interpretation should apply regardless of thebreadth of the range or the characteristics being described.

THE INVENTION

Referring now to FIG. 1, a semiconductor-on-insulator (SOI) device isshown generally at 200 in accordance with one embodiment of the presentinvention. A substrate 202 can be included to provide support and/orfunctional properties to the SOI device. Any number of materials can beused as a substrate material. Typically, the substrate can be formed ofa material having desirable properties for a particular application. Forexample, in some embodiments, mechanical strength, thermal expansion,thermal conductivity, electrical resistivity, and the like can beimportant. Several non-limiting examples of suitable substrate materialsinclude tungsten, silicon, silicon carbide, silicon nitride, titaniumcarbide, titanium nitride, boron nitride, graphite, other ceramics,glass, molybdenum, zirconium, tantalum, chromium, aluminum nitride, DLC,and composites thereof. A substrate comprising tungsten can provideexceptional mechanical support as well as low thermal expansion.Similarly, a substrate comprising silicon can be highly compatible withincorporation into various semiconductor devices and/or products.Although many materials can act as a suitable substrate, materialshaving a low thermal coefficient of expansion are preferred. This is atleast partially in consideration of reducing thermal expansion stressesat the interface between the substrate and an adjacent material, e.g.DLC, silicon, gallium nitride, gallium arsenide, etc.

An adynamic diamond layer 204 can also be on the substrate 202. Theadynamic diamond layer can have a device surface 210 distal to thesubstrate. The adynamic diamond layer can comprise a diamond-containingmaterial. Typically, the adynamic layer is grown using a vapordeposition method, as discussed below in connection with the methods ofthe present invention. The adynamic diamond layer can have a number ofspecial properties which are advantageous for use in SOD devices.Generally, the diamond layer can have a thickness from about 10 nm toabout 100 μm, and in some cases about 100 nm to about 30 μm. Further,the diamond layer thicknesses of less than about 10 μm can be suitablefor some applications. In one specific embodiment, the diamond layer canhave a thickness from about 10 nm to less than 100 μm. Frequently, anadynamic diamond layer having a thickness of less than about 30 μm canprovide desired insulating affects, while also minimizing productiontime and costs.

An additional consideration includes the surface roughness of the devicesurface 210. More specifically, a very smooth device surface can have anumber of desirable effects. Some of these considerations include:adherence of semiconductor layers thereto, improved resolution offeature formation, improved coupling coefficients, and the like. Forexample, the methods and devices described herein focus primarily on SODdevices, exclusive of any features or semiconductor devices which can beformed thereon, subsequent to, or in combination with, the methodsdescribed herein. During fabrication of various devices, the focal depthof a light source can influence the resolution and minimum feature size,e.g., line width, etc., achievable using specific equipment. Focal depthrefers to the depth for which an image is in focus on the surface of awafer or other substrate. Thus, at differing depths, an exposed imagecan have a deteriorating focus or line edge acuity. Typical focal depthsare in the range of 1 μm to 2 μm, although ranges outside this areknown. In addition, a rough surface can interfere with this resolution,especially as the degree of surface roughness approaches the focal depthof the particular equipment used. Therefore, as surface roughness of anexposed surface is reduced, an increase in resolution and devicedensities can be achieved. In other words, in some cases, the surfaceroughness can be a limiting factor for device resolutions and densities.

In accordance with the present invention, surface roughness can besignificantly reduced without polishing expensive layers of diamond orsilicon. This aspect will be discussed in more detail below inconnection with certain methods. As a result, the primary limitation toachievable resolutions can then be the equipment used instead of thewafer or materials exposed. As an example, the device surface 210 canhave a surface roughness (Ra) from about 1 nm to about 1 μm, andpreferably from about 1 nm to about 20 nm, and most preferably fromabout 1 nm to about 10 nm.

A semiconductor layer 206 can be coupled to the device surface 210 ofthe diamond layer 204. The semiconductor layer can be directly coupledto the device surface or can be coupled via an additional layer. Thesemiconductor layer can comprise any material which is suitable forforming electronic devices, semiconductor devices, or the like. Mostsemiconductors are based on silicon, gallium, indium, and germanium.However, suitable materials for the semiconductor layer can include,without limitation, silicon, silicon carbide, gallium arsenide, galliumnitride, germanium, zinc sulfide, gallium phosphide, gallium antimonide,gallium indium arsenide phosphide, aluminum gallium arsenide, galliumnitride, boron nitride, aluminum nitride, indium arsenide, indiumphosphide, indium antimonide, indium nitride, and composites thereof. Inone embodiment, the semiconductor layer can comprise silicon, siliconcarbide, gallium arsenide, gallium nitride, aluminum nitride, orcomposites of these materials. In some additional embodiments,non-silicon based devices can be formed such as those based on galliumarsenide, gallium nitride, germanium, boron nitride, aluminum nitride,indium-based materials, and composites thereof. Other semiconductormaterials which can be used include Al₂O₃, BeO, W, Mo, c-Y₂O₃,c-(Y_(0.9)La_(0.1))₂O₃, c-Al₂₃O₂₇N₅, c-MgAl₂O₄, t-MgF₂, graphite, andmixtures thereof. However, currently, most semiconductor devices aresilicon based.

Referring now to FIG. 2, the semiconductor layer 206 can be coupled tothe device surface 210 using an intermediate layer 208. The intermediatelayer can provide a number of benefits, such as, but not limited to,improved thermal expansion matching, providing improved lattice matchingfor epitaxial growth, providing specific electronic properties, thermalconduction, and the like. Non-limiting examples of suitable material forthe intermediate layer can include aluminum nitride, chromium nitride,silicon, silicon carbide, silicon nitride, tungsten carbide, galliumnitride, tungsten carbide, boron nitride, W, Mo, Ta, Cr, and compositesor alloys thereof. In some embodiments, the intermediate material cancomprise aluminum nitride, chromium nitride, silicon nitride, tungstencarbide, gallium nitride, and composites thereof. In yet anotheradditional embodiment, the intermediate layer can comprise a materialselected from the group consisting of aluminum nitride, chromiumnitride, tungsten carbide, and composites thereof. Currently, theintermediate layer can be preferably aluminum nitride. Aluminum nitridecan be beneficial since epitaxial growth of typical semiconductormaterials, e.g., silicon and gallium based materials, thereon isfacilitated with improved lattice matching.

Alternatively, an optional intermediate layer can comprise anelectrically conductive material. Non-limiting examples of suitableconductive materials can include copper, aluminum, tungsten, tantalum,and alloys thereof. This optional intermediate layer can be included toprovide a unique option of designing semiconductors having positive andnegative electrodes on either side of the insulating layer.

Typically, the intermediate layer can have a thickness such that thecontours and smoothness of the adynamic layer are substantiallyunaltered. However, some variation can occur, common thicknesses canrange from about 50 nm to about 10 μm, and preferably about 400 nm toabout 5 μm, depending on the specific application and device.

Referring now to FIGS. 3A through 3D, one method for making an SODdevice in accordance with the present invention is shown. FIG. 3Aillustrates a mold 220 having an interface surface 212 configured toinversely match a configuration intended for a device surface 210 of theSOI device. The mold used in the methods of the present invention can beof any material sufficient to withstand the vapor deposition and/orother layer formation processes, and allow the formation of a diamondfilm, or other intermediate layer thereon. Additionally, the mold can bedesigned to form a single or multiple SOD devices from which individualfinal SOD devices can be recovered. As a general overview of thefollowing discussion, once the adynamic diamond layer is grown, the moldcan be completely removed or only partially removed. The mold cancomprise almost any suitable material, and in some cases can comprise amaterial suitable for use as the intermediate and/or semiconductorlayers.

Although many materials can be used, the mold can comprise tungsten,silicon, titanium, chromium, zirconium, molybdenum, tantalum, manganese,carbides of these metals, ceramics, and composites or alloys thereof.However, in one aspect, the mold may be made of, or substantially madeof, a metallic material. The metallic material may be a member selectedfrom the group consisting of aluminum, copper, tungsten, molybdenum,tantalum, zirconium, vanadium, and chromium. In another embodiment, themold may be made of, or made substantially of, non-metals, such ascarbides and ceramics, including glass, oxide, and nitride materials.Examples of carbide materials include without limitation, tungstencarbide (WC), silicon carbide (SiC), titanium carbide (TiC), zirconiumcarbide (ZrC), and mixtures thereof among others. Examples of oxidematerials include without limitation, quartz (i.e. crystalline SiO₂),corundum or sapphire (i.e. Al₂O₃), LiTaO₃, LiNbO₃, ZnO, and mixturesthereof. Examples of nitride materials include without limitation,silicon nitride (Si₃N₄), aluminum nitride (AlN), boron nitride (BN),titanium nitride (TiN), zirconium nitride (ZrN), and mixtures thereof,among others. Examples of glass include all types of glass includingsoda glass, etc. Alternatively, the mold can comprise a materialsuitable for use as a semiconductor or intermediate layer as disclosedearlier.

The mold can be polished to form a very smooth interface surface 212.Polishing the mold interface surface may be accomplished using a varietyof methods known to those skilled in the art; however, use of micron ornano-sized diamond particles during the polishing step can also providea good nucleation enhancing layer for vapor deposition of diamond. Theinterface surface can be polished to a surface roughness correspondingto a desired surface roughness of the device surface 210. Certainnon-metallic materials, such as the carbide and ceramic materialsrecited above are particularly well suited for use as a mold in thepresent invention because of their hardness and ability to achieve anextremely smooth interface surface. A smooth interface surface isparticularly important when making a SOD device that requires a smoothdevice surface. In many cases, the interface surface of a ceramicmaterial may be polished to have a surface roughness of less than about10 μm. In other instances, the surface roughness can be less than about5 μm. Depending on the device, a surface roughness of less than about 1μm can provide good results. In some cases, an ultra smooth surface canbe desirable and may be less than about 20 nm. As line width resolutionsdecrease, a surface roughness of less than 1 nm can also be beneficialin providing improved exposure resolutions and image acuities. Variousmethods for polishing the interface surface to achieve such a degree ofsmoothness, for example with diamond or nanodiamond powder or paste, orother diamond tools are well known to those skilled in the art.

Referring again to FIG. 3A, an adynamic diamond layer 204 can be grownon the mold 220 using a vapor deposition technique. Any number of knownvapor deposition techniques can be used to form the adynamic diamondlayer. The most common vapor deposition techniques include CVD and PVD,although any similar method can be used if similar properties andresults are obtained. Currently, the preferred diamond growth method isCVD techniques such as hot filament, microwave plasma, oxyacetyleneflame, and direct current arc techniques. The reactant gases used duringsuch techniques may be any which are known in the art as useful forsafely accomplishing diamond layer fabrication using a selected CVDtechnique. However, in one aspect, the gases used in the CVD techniqueare a combination of methane and hydrogen gases. The adynamic diamondlayer can have a thickness as described above. However, in some cases aslightly thicker layer of diamond can be formed and then the growthsurface can be carefully polished to the desired thickness.

An optional nucleation enhancing layer can be formed on the interfacesurface in order to improve the quality and deposition time of thediamond layer. Specifically, the diamond layer device surface can beformed by depositing applicable nuclei, such as diamond nuclei, on theinterface surface of a mold and then growing the nuclei into a film orlayer using a vapor deposition technique. While ceramics and othernon-metal materials are able to achieve a smooth interface surface, manyof these materials, such as oxides, are unable to nucleate diamond andretain it in place very well. Therefore, in order to overcome such adeficiency, in one aspect of the present invention, a thin nucleationenhancer layer can be coated upon the interface surface of the mold.Diamond nuclei are then placed upon the nucleation enhancer layer, andthe growth of the diamond layer proceeds via CVD as described herein.

A variety of suitable materials will be recognized by those in skilledin the art which can serve as a nucleation enhancer. In one aspect ofthe present invention, the nucleation enhancer may be a materialselected from the group consisting of metals, metal alloys, metalcompounds, carbides, carbide formers, and mixtures thereof. Examples ofcarbide forming materials include without limitation, tungsten (W),tantalum (Ta), titanium (Ti), zirconium (Zr), chromium (Cr), molybdenum(Mo), silicon (Si), and manganese (Mn). Additionally, examples ofcarbides include tungsten carbide (WC), silicon carbide (SiC), titaniumcarbide (TiC), zirconium carbide (ZrC), and mixtures thereof amongothers.

The nucleation enhancer layer, when used, is a layer which is thinenough that it does not to adversely affect the transfer of the intendedconfiguration from the interface surface to the device surface. In oneaspect, the thickness of the nucleation enhancer layer may be less thanabout 0.1 micrometers. In another aspect, the thickness may be less thanabout 10 nanometers. In yet another aspect, the thickness of thenucleation enhancer layer is less than about 5 nanometers. In a furtheraspect of the invention, the thickness of the nucleation enhancer layeris less than about 3 nanometers.

As the nucleation surface of the diamond layer can be the device surfaceof the tool, care should be taken to ensure that this surface is of thehighest quality and integrity possible. Different degrees of quality maybe achieved during the vapor deposition process, as required by theparticular device being fabricated. Those of ordinary skill in the artwill readily recognized the differing conditions and techniques whichproduce a given degree of quality, and will be able to achieve variousdegrees of quality without undue experimentation.

Various methods may be employed to increase the quality of the diamondin the nucleation surface of the diamond layer which is created by vapordeposition techniques. For example, diamond particle quality can beincreased by reducing the methane flow rate, and increasing the totalgas pressure during the early phase of diamond deposition. Suchmeasures, decrease the decomposition rate of carbon, and increase theconcentration of hydrogen atoms. Thus a significantly higher percentageof the carbon will be deposited in a sp³ bonding configuration, and thequality of the diamond nuclei formed is increased. Additionally, thenucleation rate of diamond particles deposited on the diamond interfacesurface of the mold or the nucleation enhancer layer may be increased inorder to reduce the amount of interstitial space between diamondparticles. Examples of ways to increase nucleation rates include, butare not limited to: applying a negative bias in an appropriate amount,often about 100 volts, to the diamond interface surface of the mold;polishing the diamond interface surface of the mold with a fine diamondpaste or powder, which may partially remain on the interface surface;and controlling the composition of the diamond interface surface such asby ion implantation of C, Si, Cr, Mn, Ti, V, Zr, W, Mo, Ta, and the likeby PVD or PECVD. Physical vapor deposition (PVD) processes are typicallyat lower temperatures than CVD processes and in some cases can be belowabout 200° C. such as about 150° C. Other methods of increasing diamondnucleation will be readily apparent to those skilled in the art.

Polishing with diamond powder or paste is especially useful when anultra-smooth interface surface is desired. Further, when a fine diamondpaste is used to polish the interface surface, many diamond particlesmay become embedded in the diamond interface surface, and can serve asseeds for increased nucleation rates. Certain metals, such as iron,nickel, cobalt, and their alloys, are known to catalyze diamond intoamorphous carbon or graphite at high temperatures (i.e. greater than700° C.). Thus, by limiting the amount of such substance in thecomposition of the interface surface of the mold, the amount of diamondwhich will be catalyzed to graphite is greatly reduced, and the overallquality of the nucleation surface is increased.

In one more detailed aspect of the present invention, the interfacesurface of the mold can be etched with micro-scratches to enhancenucleation. One method of introducing such micro-scratches is to immersethe mold in an acetone bath containing suspended micron-size diamondparticles. Ultrasonic energy can then be applied to the mold and/or thefluid. Upon removal of the mold from the ultrasonic bath, a portion ofthe micron-sized diamonds remains on the surface as diamond growthseeds.

In another detailed aspect of the present invention, nucleation can beoptionally enhanced by applying an electrical current such that a strongnegative bias is created at the mold. An applied voltage of about 120volts can increase nucleation density up to a million fold.

In one aspect, tungsten carbide may be used as the material for themold, including the diamond interface surface thereof. However, bylimiting the amount of cobalt binder contained therein to less thanabout 4% w/w, the incidence of diamond catalysis is greatly reduced.Further, it has been found that binder free tungsten carbide materialsmay be used to greatly reduce diamond catalysis. Additionally, it hasbeen found that using ultra fine or sub-micron tungsten carbide grainscreates a very smooth diamond interface surface which increases diamondnucleation. Additionally, the smooth micro-configuration of theinterface surface is imparted to the device surface of the diamondlayer.

Referring again to FIG. 3A, the device surface 210 can be produced atthe interface surface 212 of the mold 220 as the diamond layer 204grows. As the diamond layer grows, the growth surface becomesincreasingly rough. Once the CVD process is complete, the growth surface222 remains exposed and is typically rough compared to the devicesurface. As mentioned above, the adynamic diamond layer is notself-supporting such that if the mold were removed leaving only thediamond layer, the layer would curl or otherwise lose its intendedshape, resulting in an unsuitable surface for use in a SOD device.Typically, the thickness of the adynamic diamond layer is less thanabout 30 μm such as between about 5 μm and about 20 μm, although otherthicknesses may be suitable for particular applications.

FIG. 3B illustrates one embodiment of the present invention. In order toprevent deformation of the adynamic layer, a substrate 214 can be joinedto the growth surface 222 of the adynamic diamond layer 204 prior toremoving the mold 220 or a portion thereof in order to prevent curlingof the adynamic diamond layer. In one aspect of the present invention,the substrate can be joined to the growth surface of the adynamicdiamond layer by brazing. A variety of brazing alloys may be suitablefor use in the present invention. Of particular benefit are braze alloyswhich include a carbide former such as Ti, Cr, Si, Zr, Mn, and mixturesthereof. Several exemplary braze alloys include those of Ag—Cu—Ti,Ag—Cu—Sn—Ti, Ni—Cr—B—Si, Ni—Cu—Zr—Ti, Cu—Mn, and mixtures thereof. Thebrazing alloy may be supplied in any known form such as a powder or as athin foil. Typical brazing temperatures are below about 1000° C. such asabout 900° C.

Further, the substrate can preferably comprise a material having athermal expansion which is comparable to that of diamond in order toprevent damage to the adynamic diamond layer upon cooling from thebrazing temperatures. Brazing to the growth surface of the diamond layerhas the added advantage in that the growth surface is rough, increasingthe strength of the braze bond between the diamond layer and thesubstrate.

In some embodiments of the present invention, it may be desirable to usea non-carbide forming material for the mold. For example, when the moldis a non-carbide forming material such as copper, the diamond layer willseparate from the mold upon cooling. Either before or after cooling abraze foil may be placed on the growth surface of the adynamic diamondlayer. Subsequently, a substrate is placed against the braze foil andthe assembly is pressed together under heat, and optionally vacuum, inorder to braze the diamond layer to the substrate. In this embodiment,the mold is not attached to the diamond layer and may be easily removed.

Alternatively, the device surface of the adynamic diamond layer may beplaced against a pressing surface which may be optionally coated with alayer of material which prevents bonding of the pressing surface to thediamond layer, such as an aerosol containing boron nitride. The brazefoil may then be placed against the growth side of the adynamic diamondlayer by carefully flattening the curved diamond layer followed bypressing the substrate against the braze foil and brazing the assemblyas described above. Following joining the substrate, a portion of, orthe entire mold can be removed without damaging the adynamic diamondlayer. The device surface of the diamond may be polished to remove anyresidual graphitic bonds, but is often not required to achieve thenecessary smooth finish Any such polishing would be minimal and would beon the order of angstroms, occasionally on the order of nanometers,rather than microns.

Additionally, the substrate can be joined to the growth surface eitherbefore or after coupling the semiconductor layer. Typically, thesubstrate can be joined before coupling of the semiconductor layer asdescribed above. However, as discussed herein, if the mold is used toform the intermediate layer or semiconductor layer, the substrate can bejoined to the growth surface subsequent to formation of thesemiconductor layer and or devices thereon. The particular choice oforder of forming individual layers can depend on processingconsiderations such as convenience, strength of the layers, pre-existingequipment layout, and the like.

In one aspect, multiple layers of diamond may be deposited over oneanother using vapor deposition techniques while in the mold, or afterthe initial diamond layer has been formed and removed from the mold toform a consolidated layer of desired thickness. In one aspect, thediamond layer may be thickened after the deposition of the initial film,using non-vapor techniques, as are known in the art of diamondfabrication and consolidation. In another aspect of the invention, suchthickening may take place while the initial diamond layer is still inthe mold, or after it has been removed (e.g. by dissolution in acid orKOH).

Depending on the specific embodiment the entire mold can be removed oronly a portion thereof. FIG. 3C illustrates an embodiment wherein theentire mold is removed to expose the device surface 210 of the adynamicdiamond layer 204. The mold and/or optional nucleation enhancer layercan be separated from the diamond layer using any mechanism suitable forremoving the particular substance from which the mold and nucleationenhancer layer is fabricated. In one aspect of the present invention,the mold can be chemically removed from the diamond, such as bydissolution thereof with acid or a base solution such as KOH or byplasma etching. In another aspect, the mold can be physically removedfrom the diamond layer, for example by grit blasting or mechanicalpolishing. In yet another aspect, the mold can be removed from thediamond layer using a heat or cold treatment, such as a furnace formelting the mold, or liquid nitrogen for freezing and crumbling themold. In a further aspect, separation of the mold from the diamond layerdue to heating or cooling may be merely a result of different thermalexpansion properties between the mold material and the diamond material.

In accordance with the embodiment shown in FIG. 3D, a semiconductorlayer 206 can be coupled to the device surface 210 of the adynamicdiamond layer 204. The semiconductor layer can comprise any of thematerials previously discussed or any other material suitable forconstruction of a particular device thereon. In another aspect of theinvention, the semiconductor material can be obtained from a singlecrystal ingot in order to control the crystal orientation, reducecrystal defects, and provide a high electromechanical coupling factor.The single crystal ingot can be typically formed from a molten liquidrather than the vapor phase. Further, the single crystal ingot typicallyhas a significantly lower defect content than crystals formed from usingvapor deposition. Also, this eliminates concerns regarding epitaxialgrowth of the semiconductor layer on diamond-containing materials whichcan be difficult.

Further, additional components can be formed upon the exposed devicesurface of the diamond layer after removal of the mold, and nucleationenhancer layer if used. The types of devices which can be fabricatedusing the process of the present invention are any device for which anadvantage may be found for incorporating diamond as an insulation layer.The SOD devices of the present invention can be incorporated intovarious electronic devices such as, but not limited to, logic chips,memory storage, light emitting diodes, e.g., blue LEDs, microwavegenerators, and other semiconductor devices. Those skilled in the artwill recognize the potential advantages of SOD devices of the presentinvention and the methods by which such devices can be incorporated intovarious devices such as those mentioned above or other semiconductordevices. One significant advantage in many applications which require avery smooth device surface, is that because little or no device surfacemachining is necessary after removing the mold, the number ofvariations, microcracks or fissures which are caused by such machiningis substantially reduced, or eliminated. The reduced incidence ofvariations, including micro cracks on the device surface greatlyenhances the quality of the final product. Further, semiconductordevices and or features can be formed on the semiconductor layer eithersimultaneous with steps discussed herein or in separate steps accordingto known semiconductor fabrication techniques.

Alternatively, the mold can also serve as the substrate. In this case,the growth surface can most likely require polishing prior to couplingthe semiconductor layer.

FIGS. 4A through 4C illustrate another alternative embodiment wherein atleast a portion of the mold is left in place to form a layer of the SODdevice. FIG. 4A illustrates an adynamic diamond layer 204 formed on thedevice surface 212 of a mold 220. A substrate 214 can be formed orattached as discussed previously. Alternatively, the substrate can beattached subsequent to removal of a portion of the mold.

As shown in FIG. 4B, the mold 220 can be thinned to a predeterminedthickness shown by line 218. FIG. 4C illustrates the SOD device afterremoval of a portion of the mold. In such instances, the portion of themold which remains becomes an integral part of the finished device. Inorder to produce a finished product under these circumstances, in someaspects, the outside surface of the mold may be polished or shaped toprovide a desired configuration or thickness therefore, if such work hasnot been accomplished prior to the fabrication of the diamond layer. Themold can be thinned by grinding, polishing, or chemically etching to thedesired thickness.

In one aspect, the thickness of the original mold may be any thicknessor configuration required to produce a specific device. Thepredetermined thickness can be greater than about 1 millimeter and insome aspects can be greater than about 5 millimeters. In an additionalaspect, the outside surface of the mold can be polished or shaped tohave a configuration required to produce a specific device. In a furtheraspect, the mold may be polished or shaped into a layer have a thicknessof less than about 1 micrometer. In another aspect, the thickness may beless than about 0.1 micrometer.

In one embodiment, the mold can comprise a material suitable for use asthe semiconductor layer. In this case, the steps of growing the adynamicdiamond layer and coupling a semiconductor layer are achievedsimultaneously, i.e. the semiconductor layer is formed out of the mold.Examples of suitable mold materials which can also serve as thesemiconductor layer include, but are not limited to, silicon, siliconcarbide, gallium arsenide, gallium nitride, aluminum nitride, andcomposites thereof.

In an alternative embodiment, the intermediate layer can be provided byproviding a mold of suitable material and then removing only portions ofthe mold necessary, as discussed above, before coupling thesemiconductor layer thereto. Optionally, the intermediate layer can beformed after removal of the mold.

Additionally, the mold can be partially removed to expose at least aportion of the device surface. Typically, the substrate can be joinedprior to removing a portion of the mold to aid in providing mechanicalsupport. However, if only portions of the mold are removed, theremaining material of the mold can provide sufficient support in orderto allow subsequent joining of the substrate later. This alternative canbe desirable for processing convenience or other reasons such as formingmultiple devices in a single process. The semiconductor layer can becoupled to the device surface by forming the semiconductor layer on atleast the exposed portions of the device surface. Alternatively, anintermediate layer can be formed on the exposed portions of the devicesurface and then the semiconductor layer is then formed on theintermediate layer. In such embodiments, the semiconductor and/orintermediate layers can be formed by vapor deposition, brazing, gluing,or other known methods. In one preferred aspect, these layers can beformed by vapor deposition.

Some SOD devices utilize a layer of intermediate material. In one aspectof the present invention, a thin intermediate layer can be placed incontact with the smooth device surface of the diamond layer. In oneembodiment of the present invention, an intermediate layer can be placedon the interface surface prior to growing the diamond layer thereon. Insuch embodiments, the intermediate layer can comprise a material whichis suitable for nucleation and formation of diamond thereon. This canalso be enhanced by forming a nucleation enhancing layer as discussedpreviously. By depositing a thin layer of material the smooth surfaceand contours of the mold interface is retained on the depositedintermediate layer. The mold, or a portion thereof, can be removedsubsequent to the steps of growing the adynamic diamond layer and/orjoining the substrate to the growth surface.

Alternatively, an intermediate layer can be attached to the devicesurface of the diamond layer after the mold is removed. Typically, theintermediate layer can be sputtered onto the device surface of thediamond layer or otherwise grown. Such methods of depositing material ona diamond surface from a vapor phase are well known to those skilled inthe art such as CVD, PVD, or sputtering on a heated substrate.Subsequent heat treatments can be used to produce specific crystal andlattice structure suitable for a particular embodiment.

In an alternative embodiment of the present invention, it may besuitable to use a single crystal of substantial thickness. Typicalsingle crystals are grown as ingots which are then cut for use invarious devices. Additionally, in one aspect of the present invention,the single crystals can be optionally coated with a carbide former.

However, in accordance with one aspect of the present invention, thesesingle crystal blanks can be bonded to the device surface of the diamondlayer using an ultra thin layer of bonding material. Prior to bondingwith the device surface, the single crystal should be polished to asmooth finish having a surface roughness which is comparable to thecorresponding device surface. The surface roughness will depend on theintended final device. However, in some cases, a surface roughness ofless than about one nanometer, preferably less than about 5 angstroms,can be suitable. Subsequently, an ultra thin layer of bonding materialmay be produced by forming a layer of bonding material on either thedevice surface or the smooth blank surface and then pressing the twosurfaces together in order to reduce the bonding layer thickness to lessthan about 1 micron and preferably less than about 10 nanometers (i.e.only a few molecules thick). The bonding material may comprise anorganic binder such as an epoxy or may be a reactive metal such as Ti,Si, Zr, Cr, Mo, W, Mn, or mixtures thereof. In the case of a reactivemetal, the metal may be sputtered on a either the device surface or thesmooth blank surface and then pressed against the other surface underheat and vacuum conditions. At these ultra thin thicknesses, the bondingmaterial is more stable at higher temperatures. For example, typicalepoxy binders will fail at temperatures above about 200° C.; however atultra thin thicknesses the epoxy remains strong at higher temperatures.Further, SOD devices do not require the same degree of strength as inmechanical applications. Therefore, these thin layers of bondingmaterials are suitable for SOD devices. The bonded blank can then beground and polished to any desired thickness, e.g. less than about 2 μmin the case of a SOD device.

Alternatively, the SOD devices of the present invention can be formed byproviding a mold having an interface surface and growing an adynamicdiamond layer on the interface surface using a vapor depositiontechnique. A semiconductor layer can be directly coupled to the growthsurface of the adynamic diamond layer. The mold can be removed, thinned,or left in place for use as the substrate. Additionally, an intermediatelayer can be formed on the growth surface. The semiconductor layer canthen be formed on the intermediate layer. Optionally, the growth surfaceof the diamond layer can be polished prior to coupling the semiconductorlayer thereto.

In order to mass produce the SOD devices of the present invention, themold can be a wafer of sufficient size to produce multiple SOD devicesfrom a single wafer precursor. Once the adynamic diamond layer is grown,the semiconductor layer formed, and the substrate is joined, the largerwafer precursor can be subdivided into individual SOD devices.Frequently, the thermal expansion coefficients of the diamond layer andthe mold are sufficiently different to cause separation of the layers.This is typically not a problem over an area a few millimeters across,however economic mass production generally requires that such componentsbe formed on wafers and then cut from the wafers. Additionally, wafersizes are commonly up to 6 inches and newer processes utilize wafersizes of 8 or 12 inches across. Thus, the difference in thermalexpansion becomes a greater problem as the wafer size increases.

Therefore, in accordance with another aspect of the present invention,small grooves may be formed on the interface surface of the mold. Thegrooves form a grid wherein each subdivided area defines a surfacecorresponding to a single SOD device. The grooves may be formed byetching, cutting, or any other known method. As diamond, or intermediatematerial, is deposited thereon the grooves act to anchor the mold andisolate the thermal expansion differences to each grid area. Thus, asthe mold cools subsequent to the vapor deposition process, thecontraction of the mold is limited by the diamond deposited in thegrooves. For example, a single crystal piezoelectric LiNdO₃ mold canhave up to five times the thermal contraction of diamond when coolingfrom about 900° C. depending on the crystallographic orientation.

Although the grooves may be of any depth and width one currentembodiment utilizes grooves having a width and a depth of about 1 μm toabout 10 μm, and preferably about 5 μm. Any suitable method can be usedto form such grooves, e.g., diamond scriber, chemical etching, etc. Oneadvantage of using this method wherein the mold is only partiallyremoved (and incorporated into the final device) is that the depth ofthe groove can be chosen to correspond to the desired thickness of thesemiconductor layer or intermediate layer, although this is notrequired. For example, the mold would be made of a suitablesemiconductor material and after joining a substrate to the growthsurface of the adynamic layer, the mold can be polished until thediamond deposited in the grooves is exposed. In this embodiment, theremaining mold material is used in the final product.

Further, the degree of exposed diamond can be detected by a rise inelectrical resistance (as diamond is electrically insulating) across thepolishing surface. The electrical resistance can be measured across theentire wafer in order to maintain a substantially uniform thickness.Thus, for example, if the electrical resistance increasesdisproportionately on one side of the wafer, force can be increase toincrease the polishing and removal rate at the opposite side of thewafer. As a guide, the uniform depth of the grooves helps to ensure auniform thickness of semiconductor material across the entire waferprecursor. Other components can then be attached to the semiconductormaterial and final packaging materials can be layered thereon. The finaldevices can then be separated by cutting using known techniques toproduce the final devices which may then be incorporated into variousproducts. Although dimensions can vary, SOD device dimensions cantypically have about 0.5 mm total thickness, wherein the semiconductorlayer and diamond layer are up to about 30 μm.

In another variation of the above method which utilizes grooves in theceramic mold, a CVD diamond-passive material is deposited in thegrooves. Suitable CVD passive materials include any material on whichdiamond does not form under CVD conditions such as copper, silver, SiO₂,Al₂O₃, BN, graphite, and mixtures thereof. Copper is the currentlypreferred CVD diamond-passive material. During the CVD process diamondwill form at the interface surface but not on the CVD passive material.Following the completion of the SOD devices thereon, the CVD passivematerial may be removed by acid dissolution or mechanical force. Thisvariation of the present invention makes separating the individualdevices from the wafer precursor much less expensive since no cutting ofdiamond is required. In yet another alternative a CVD passive materialis deposited in a pattern which corresponds to individual SOD deviceswithout forming grooves in the surface of the mold.

EXAMPLES Example 1

A 100 mm diameter by 0.6 mm thick silicon wafer was polished to asurface roughness of less than 1 μm. The polished surface was thenscratched using a diamond scriber along grid lines to form scratchesabout 2 μm deep. The silicon wafer was then placed in an ultrasonic bathcontaining acetone and dispersed micron-sized diamond fines. Aftertreatment, the silicon wafer had a thin layer of micron-sized diamondparticles remaining on the polished surface. The silicon wafer was thenplaced in a hot filament CVD system having an atmosphere of 1% methaneand balance hydrogen at 40 torr. These conditions were maintained forabout 30 hours, during which a diamond film was deposited to about 30 μmin thickness. The diamond coated silicon wafer was removed from the CVDsystem. A tungsten disk having a 100 mm diameter and 0.5 mm thicknesswas brazed to the growth side of the diamond using NICROBRAZ LM at 1005°C. for 12 minutes under a vacuum at 10⁻⁵ torr. The silicon substrate wasthen ground to about 1 μm thickness using diamond deposited in thescratches as a guide to maintain uniformity of grinding. The silicon ondiamond wafer can then be further processed to form any number ofsemiconductor devices thereon.

Example 2

The same process was followed as in Example 1, except the tungsten diskis replaced by PVD sputtered tungsten.

Example 3

A 100 mm diameter by 0.6 mm thick silicon wafer was polished to asurface roughness of less than 1 μm. The silicon wafer was then placedin an ultrasonic bath containing acetone and dispersed micron-sizeddiamond fines. After treatment, the silicon wafer had a thin layer ofmicron-sized diamond particles remaining on the polished surface. Thesilicon wafer was then placed in a hot filament CVD system having anatmosphere of 1% methane and balance hydrogen at 40 torr. Theseconditions were maintained for about 30 hours, during which a diamondfilm was deposited to about 30 μm in thickness. The diamond coatedsilicon wafer was removed from the CVD system. A tungsten disk having a100 mm diameter and 0.5 mm thickness was brazed to the growth side ofthe diamond using NICROBRAZ LM at 1005° C. for 12 minutes under a vacuumat 10⁻⁵ torr. The silicon substrate was then completely removed bydissolving in a hot concentrated sodium hydroxide solution. The exposeddiamond surface was lightly polished and a 1 μm thick layer of aluminumnitride was deposited using PVD. The CVD process included an aluminumtarget in a nitrogen atmosphere under vacuum. The deposited aluminumnitride was found to align preferentially with the basal plane (0002),i.e. in parallel with a silicon surface. A semiconductor layer ofgallium nitride was then deposited to form an SOD device. The SOD wafercan then be further processed to form any number of semiconductordevices thereon.

Example 4

The same process was followed as in Example 3, except a single crystalof silicon was deposited on the aluminum nitride intermediate layer inplace of the gallium nitride layer.

Example 5

The same process was followed as in Example 1, except a gallium arsenidewafer was used instead of a silicon wafer. Further, a silicon wafer ofthe same dimensions was then brazed onto the CVD diamond. The galliumarsenide layer was then polished to a thickness of about 5 μm.

Of course, it is to be understood that the above-described arrangementsare only illustrative of the application of the principles of thepresent invention. Numerous modifications and alternative arrangementsmay be devised by those skilled in the art without departing from thespirit and scope of the present invention and the appended claims areintended to cover such modifications and arrangements. Thus, while thepresent invention has been described above with particularity and detailin connection with what is presently deemed to be the most practical andpreferred embodiments of the invention, it will be apparent to those ofordinary skill in the art that numerous modifications, including, butnot limited to, variations in size, materials, shape, form, function andmanner of operation, assembly and use may be made without departing fromthe principles and concepts set forth herein.

1. A semiconductor-on-diamond device, comprising: a) a mold; b) anadynamic diamond layer; and c) an intermediate layer disposed betweenthe mold and the diamond layer.
 2. The device of claim 1, wherein themold comprises a semiconductor.
 3. The device of claim 2, wherein thesemiconductor comprises at least one member selected from the groupconsisting of, silicon, silicon carbide, gallium arsenide, galliumnitride, germanium, zinc sulfide, gallium phosphide, gallium antimonide,gallium indium arsenide phosphide, aluminum gallium arsenide, galliumnitride, boron nitride, aluminum nitride, indium arsenide, indiumphosphide, indium antimonide, indium nitride, and mixtures andcomposites thereof.
 4. The device of claim 2, wherein the semiconductorcomprises an oxide material.
 5. The device of claim 4, wherein thesemiconductor comprises at least one member selected from the groupconsisting of aluminum oxide, zinc oxide and mixtures and compositesthereof.
 6. The device of claim 4 wherein the semiconductor compriseszinc oxide.
 7. The device of claim 1, wherein the intermediate layercomprises at least one material selected from the group consisting ofaluminum nitride, chromium nitride, silicon, silicon carbide, siliconnitride, tungsten carbide, gallium nitride, boron nitride, diamond-likecarbon, tungsten, molybdenum, tantalum, chromium, and composites oralloys thereof.
 8. The device of claim 1, wherein the intermediate layercomprises an electrically conductive material.
 9. The device of claim 8,wherein the electrically conductive material comprises at least onemember selected from the group consisting of copper, aluminum, tungsten,tantalum and alloys thereof.
 10. A semiconductor-on-diamond device,comprising: a) a mold; b) a diamond layer having a thickness from about10 nm to about 100 μm; and c) an intermediate layer disposed between themold and the diamond layer.
 11. The device of claim 10, wherein thediamond layer comprises a diamond-containing material.
 12. The device ofclaim 11, wherein the diamond-containing material comprises at least onemember selected from the group consisting of natural diamond, syntheticdiamond, polycrystalline diamond, diamond-like carbon, amorphousdiamond.
 13. The device of claim 12, wherein the diamond-containingmaterial comprises synthetic diamond.
 14. The device of claim 10,wherein the intermediate layer comprises a nucleation enhancingmaterial.
 15. The device of claim 14, wherein the nucleation enhancingmaterial is selected from the group consisting of metals, metal alloys,metal compounds, carbides, carbide formers, and mixtures thereof. 16.The device of claim 15, wherein the carbide formers comprise at leastone member selected from the group consisting of tungsten, tantalum,titanium, zirconium, chromium, molybdenum, silicon, and manganese. 17.The device of claim 15, wherein the carbides comprise at least onemember selected from the group consisting of tungsten carbide (WC),silicon carbide (SiC), titanium carbide (TiC), zirconium carbide (ZrC),and mixtures thereof.
 18. The device of claim 10, wherein theintermediate layer is electrically conductive.
 19. A method of making asemi-conductor on diamond (SOD) device comprising the steps of:providing a mold having an interface surface; forming an intermediatelayer on the interface surface of the mold; growing a diamond layer onthe intermediate layer.
 20. The method of claim 20, wherein in growingthe diamond layer is accomplished by using a vapor deposition technique.21. A method of making a semiconductor-on-diamond (SOD) devicecomprising the steps of: providing a mold having an interface surface,the mold comprising a semiconductor; forming an intermediate layer onthe interface surface of the mold; growing a diamond layer on theintermediate layer using a vapor deposition technique; and removing atleast a portion of the mold.
 22. A method of making asemiconductor-on-diamond (SOD) device comprising the steps of: providinga mold having an interface surface configured to inversely match aconfiguration intended for a device service of the SOD device; formingan intermediate layer on the interface surface of the mold; growing adiamond layer on the intermediate layer using a vapor depositiontechnique; and completely removing the mold thereby exposing a diamonddevice surface; and forming a semi-conductor layer on the exposeddiamond device surface.